A PND is a convenient tool for a driver. With preferred planned routes provided by the PND, the driver can obtain a current position and avoid getting lost or taking an undesired detour. In addition, by the PND a user can watch TV programs anywhere, in a vehicle or outdoors, no longer limited to indoors.
Nowadays, a PND with a TV function can be classified into several architecture types.
The first architecture is that a PND has two processing modules independent from each other. One processing module is used for processing Global Positioning System (GPS) signals from satellites; the other processing module is used for processing TV signals. Both of the processing modules, without sharing interface, have respective elements such as a display interface, a sound interface or a data bus. Therefore, the first architecture suffers from disadvantages of having high costs, large-area circuits, high degrees of design complexity, high power consumption and so on.
The second architecture is that a PND only has a single processing module which needs to be powerful enough to simultaneously process GPS signals and TV signals. The second architecture has disadvantages below. First of all, a high speed processing unit having high computation capability is needed; secondly, high power consumption by the processing unit is resulted from processing images and voices; last but not least, concurrent execution of a navigation function and a TV function is unlikely to be smooth with the single processing module.
Accordingly, it is preferred to provide a PND, which comprises dual processing units that share common system resources and is capable of providing a navigation function and a TV function. Such PND not only solves the foregoing problem and other problems of the prior art, but also has advantages that are not provided by the conventional technology.